1. Field of the Invention
The present invention relates to a wireless communication device such as a wireless LAN (Local Area Network), and to a control method for such a device.
2. Description of the Related Art
Conventionally, it has been easy to configure a LAN, and Wireless LANs have been drawing attention due to their advantages, such as the fact that is possible to easily connect mobile terminals such as mobile game terminals, for example, to a network at outside destinations.
With this type of wireless LAN, communication is carried out by selectively using one of a plurality of frequency bands (channels), and in order to determine whether or not a channel is busy (in a state of being used by another user) a method of detecting energy level of a signal received at the frequency band of the channel or a method of detecting a carrier is used.
Of these methods, the method of detecting a carrier can reliably detect the presence or absence of a user compared to the method of detecting energy level, but is characterized in that a long time is taken until detection. On the other hand, the method of detecting energy level has low detection precision at points where it detected that another user is communicating, even if there is no other user communicating, if the energy level of a received signal is high in a channel frequency band due to noise etc. generated in the ambient surroundings.
On the other hand, in a portable game machine, it is necessary to send and receive information relating to the game in real time. For that reason, as a method for determining whether transmission of information is possible, confirmation of the fact that another user communicating by the method of detecting a carrier is not realistic because a comparatively long time is taken for detection with this method.
However, in the case where the method using energy level is adopted, there are the following problems. That is, in recent years game machines have also become highly function rich, and this itself leads to a lot of noise sources, meaning there are a lot of erroneous detections due to setting of energy levels, and it can be assumed that communication opportunities will be compromised.